Spray coating mechanism



G. G. SCHNEIDER EI'AL 2,470,

SPRAY COATING MECHANISM May 17, 1949.

4 Sh eets-Sheet 1 Filed Nov. 2, 1944 def/[1y s ATTORNEY G- G. SCHNEIDER ETAL 2,470,580

May 17, 1949.

SPRAY COATING MECHANISM Filed Nov. 2, 1944 {Sheets-Sheet 2 ATi'OR N EY ATTORNEY y G. e. SCHNIbER ETAL 2,470,580

SPRAY COATING MECHANISM 4 Sheets-Sheet 4 Filed Nov. 2, 1944 all/g;

ATTORNEY Patented May 17, 1949 UNITED STATES PATENT OFFICE 2,470,580 SPRAY OOATINGMECHANISM Gerhard Gunther Schneider, Maplewood, and Clifford J. Hughes, East Orange, N. J., ass'ignors to National Union Radio Corporation, Newark, N. J., a corporation of Delaware Application November 2,1944, Serial No. 561,592

1 7 Claims.

The invention herein disclosed relates to a mechanism for coating pieces with a coating material. More particularly the invention relates to a mechanism of this kind that is suitable for coating both sides of small flat pieces such, for example, as the pieces of mica used in vacuum tubes.

Small pieces of mica, of various shapes, sizes and thicknesses are used in the construction of vacuum tubes for radios. These pieces of mica must be coated on both sides with a suitable coating material. Heretofore, and prior to the invention herein disclosed, it had been common practice to lay such pieces on a tray and manually spray the upturned surface with the coating material inliquid form. The tray wasthen placed in anoven for a suitable period after which it was removed and the pieces turned over manually, one by one, and coated on the other side.

This is a time-consuming, laborious and expensive procedure.

.It is an object of the invention herein disclosed to provide a mechanism in which pieces, such as the mica pieces mentioned, are mechanically coated on one side, turned over andcoated on the other side. Another object of the invention is to provide in such a mechanism suitable regulation for controlling the thickness of the coating applied. A further object of the invention is to provide such a mechanism that is suitable for continuous operation.

The foregoing objects and certain advantages that will hereinafter app ar are realized in the embodiment of the invention illustrated in the accompanying drawing and described in detail below from which description a clearer understanding of the invention may be had.

The drawings include:

Fig. 1 which is a side elevation, with the transfer mechanism removed and partly in section and in part diagrammatic, of a mechanism illustrating one embodiment of the invention;

,. Fig. 2 which is a plan of the same;

- Fig. 3 which is a partial, sectional plan of the same taken on the line 3--3 of Fig. 1;

Fig. 4 which is an elevation of the transfer and turn-over mechanism; and Fig. 5 which is a diagram of the connections material is dried and solidified, and discharges the pieces, through a transfer and turn over mechanism E (Fig. 4) on to the conveyor B. When received on the conveyor B, the coated sur face is turned down and the uncoated surface is turned up. In this position, the conveyor B carries the pieces through another spray chamber F and a heating chamber G and then discharges the pieces into a container provided at the discharge end of the conveyor B.

The mechanism includes a frame consisting of standards I and longitudinal supporting, members 2 extending between and secured to the standards I. On this frame. the various shafts for carrying and driving the conveyors are mounted as is also the spraying and heating chambers. The conveyor A is mounted at a higher elevation than the conveyor B and includes a continuous belt 8 that may desirably be a metal link conveyor belt of a kind well-known in the art. This-belt extends over two pulleys, l and 5 at opposite ends of the frame, between which it is stretched to provide a horizontal section or portion 6 on which the pieces to be coated are carried. The pulley 4 is flxedon a shaft 1 journaled in bearing brackets 8 and 9, and the pulley 5 is fixed on a shaft Ill journaled in bearing brackets II and I2. From the pulley 5, the belt extends over an idler supporting pulley l3, under a tension pulley l4, and over an idler pulley l5 to the pulley 4.

Mounted on the frame, there is a platform support I6 for the belt 3 which is located just forward, as regards the movement of the belt, of the spray chamber C. The spray chamber desirably consists of sheet metal walls I! and is rectangular in plan. It is open at the top and connected below the belt to suction ducts (not shown). Slots l8 are provided in opposite walls for the passage of the belt through the chamber. A spray head 19, through which coating mate'- rial is sprayed into the chamber in the direction of the belt, is mounted at the open, upper end of the chamber above the belt. Some of the coating material collects on the side walls of the spray chamber and troughs 20 and 2| are provided to collect this material.

A spray head which is operated continuously soon clogs and requires cleaning. By intermittently shutting off the spray head, the rush on opening tends to prevent accumulations and keeps the spray head clean. The conveyor belt is, however, driven continuously. By properly locating the spray head in relation to the conveyor, the spray head maybe quickly cut-off and on at intervals without any lack of continuity of the coating spray at the belt. For this purpose the spray head is mounted at a distance from the conveyor belt such that while the spray is instantaneously cut-off and on at timed intervals, a continuous mist of coating composition is maintained in the spray chamber at the plane of the belt. The supply and control of the spray head is illustrated in Fig. and is hereinafter described. Regulation of the flow of coating materials regulates the thickness of the coating applied.

Following the spray chamber the heating or bakingcompartment D is mounted on the frame and opened at both ends for the passage therethrough of the conveyor belt. Desirably, the

strips 22,

When pieces carried on the belt pass through the chamber D and approach the discharge end of the belt 3, at the pulley 5, they are engaged by the transfer and turn over mechanism E (Fig. 4). This mechanism is mounted on the frame adjacent the pulley 5. A bracket 23, rotatably supports a shaft 24 to which a pulley or drum.25 is secured for rotation therewith. A

continuous flexible belt 26 passes around the pulley 25, an idler pulley 21 and a tension pulley 28. The pulley 25 is mounted rearwardly of the pulley 5, and the idler and tension pulleys are mounted forwardly of the rear of the pulley 5 and below and above the pulley 5 respectively. The belt 26, therefore, engages the conveyor belt above the pulley 5 and passes partially around the pulley 5 with the conveyor belt 3.

In this manner pieces on the conveyor belt 3 are engaged between the belts 3 and 26 and carried partially around the pulley 5 and transferred to the belt 26 with the coated side against the belt. Adjacent the idler pulley 21 there is a blade or chute 29 onto which the pieces are delivered from the belt 26. The pieces slide ,down thel chute onto the receiving end of the conveyor 13 which is below the discharge end of the conveyor A and are deposited on the conveyor belt 38 of the conveyor B with the coated side against the belt and the uncoated side turned up. The drum 25 is positively driven, as hereinafter described, to avoid any friction between the opposing belts 3 and 26. Preferably, the belt 26 is made of a soft, pliable material, such as canvas, rubber, etc., to prevent injury to the mica pieces.

The tension pulley 28 is mounted on a shaft 3| extending between and journaled in the spaced arms of a pivotally mounted bracket 32. The bracket 32 is pivotally mounted at one end on the frame at 33. A spring 34 acting between the other end of the bracket and an upright 35, fixed to the frame, keeps the belt 26 under tension,

and in engagement with the conveyor belt 3.

The conveyor B extends, as shown, at on angle to the conveyor A and it is mounted at a lower elevation than the conveyor A. The conveyor belt 36 extends over and is stretched between end pulleys 36 and 31. From the pulley 31, the belt passes below an idler pulley 38, a tension pulley 39 and over an idler pulley 46. The tension pulley is rotatably mounted in a bracket 41 that is pivoted at one end to 2. depending standard 42. Springs 43 acting between the other end of the bracket and the frame serve to exert a force which places a tension on the conveyor belt. In like manner, a spring 44 serves through a. pivoted bracket 45, in which the tension pulley I4 is mounted, to place the conveyor belt 3 under tension.

chamber is heated by electric, resistance heater The conveyor belt 38 passes through the spray chamber F and the heating chamber G which are in all respects similar to the spray chamber 0 and heating chamber D. At the pulley 36, which constitutes the discharge end of the conveyor B, the

pieces coated on both sides are discharged into a container (not shown).

Both conveyors are desirably driven from a prime mover, such as an electric motor 46 mounted on a platform 41. The motor is coupled, through a belt drive 48, to a speed reducin gear 49 on the driving shaft of which there is a sprocket 50. A chain 5| connects the sprocket 58 with a sprocket 52 secured on a drive shaft 53. The drive shaft 53 has a universal joint 54 therein and extends through the part of the frame in which the conveyor B is mounted. A chain 55 connects a sprocket 56 mounted on the shaft 53 with a sprocket 51 secured on the shaft III on which the pulley 5 is mounted. The drive shaft is coupled to the shaft on which the pulley 31 of the conveyor B is mounted through spur gears 58 and 59. The pulleys 4 and 5 are connected together by a chain 60 and sprockets 6i and 62, and the pulleys 36 and 31 are connected together by a chain. 63 and sprockets 64 and 65. The pulley 25 of the transfer mechanism E is driven by a chain 66 which extends around a sprocket 61 on the shaft l6, below and in engagement with a sprocket 68 on the shaft 24 and around an idler sprocket 69.

The ratio of the gearing and sprocket drives to the conveyors is such that the belt 30 of the conveyor B is driven at a speed greater than the speed of the conveyor A. It has been found that a difference in speed of approximately twenty percent is desirable in order to maintain the spacing of the pieces on the conveyor B. This is because control of the spacing is lost during the fall of the pieces down the chute 29 onto the belt 38 of the conveyor B.

The arrangement for supplying and controlling I the spray head IQ of the spray compartment C and a spray head 10 of the spray compartment i4 is shown in Fig. 5. There is provided a feed tank 1| for the liquid coating material. A supply line 12 extends from the feed tank to the spray head 19 and a supply 13 extends to the spray head 10.

Air under pressure is delivered from a supply to a pressure regulating valve 14 through a pipe 15. From the pressure regulating valve 14, air is supplied, through a line 16, to an air motor 11 on the feed tank and to the feed tank at approximately fifteen pounds per square inch. This air motor drives agitators (not shown) within the tank.

High and low pressure are supplied to the spray heads from the regulating valve 14. The supply to the spray heads is controlled by a manually operated valve 18 by means of which the system may be cut off. The valve 18 is in reality two valves with a single valve spindle. High pressure, of approximately seventy-five pounds per square inch, is delivered to the valve 18 through a line 19 and low or reduced pressure, of thirty pounds persquare inch, through a line 88. The low pressure air passes from the valve 18 through a line 8| to the spray head I9 and through a line 82 to the spray head 18. This is the air which effects the spray through the spray heads.

The high pressure is used to actuate the, cut-ofl valves in the spray heads. A line 83 connects the valve 18 with the inlet to a spring closed valve 84. The outlet from the valve 84 is connected by a line 85 to the spray head I8 and by a line 86 to the spray head III. The valve 84 is actuated by an electrical solenoid 81 which is energized periodically to open the valve 84 and admit air pressure to cut off the spray heads. A switch 88 controls the operation of the solenoid. This switch is spring pressed to off or open position and cam actuated to closed position. The switch is provided with a switch arm 89 having a cam follower 90 mounted on the end thereof and in the path of a four pointed cam ill. The cam is mounted on a shaft 92 that is driven through a sprocket 93 by the chain 60. As each point of the cam passes the follower 90, the switch is closed for an instant and the valve 84 is opened for an instant. Thus the spray heads arev periodically cut-off. The speed of rotation of the cam 9| or the number of points, which determine the interval between cutting-off of the spray heads, is in accordance with the fineness ofthe spray. The finer the spray, the more often the cut-off.

From the foregoing description of the embodiment of the invention shown in the drawing, it will be seen that there is provided a coating mechanism suitable for coating both sides of flat pieces continuously and automatically. It will b obvious that various changes may be made by those skilled in the art in the details of the embodiment of the invention disclosed in the drawings and described above within the principle and scope of the invention as expressed in the appended claims.

We claim:

1. In a coating mechanism of the kind described, the combination comprising a conveyor for carrying pieces to be coated, means for spraying a coating material on to the exposed surface of pieces carried by the conveyor, means for continuously driving the conveyor at a predetermined speed, a second conveyor for carrying pieces to be coated arranged with the receiving end thereof adjacent the discharge end of said first mentioned conveyor, means for spraying a coating material to the exposed surface of pieces carried by said second mentioned conveyor, means for transferring pieces from the discharge end of said first mentioned conveyor to the receiving end of said second mentioned conveyor and tuming the pieces over in the transfer, and means for continuously driving said second mentioned conveyor at a speed greater than the speed of the first mentioned conveyor to compensate for lag introduced when the pieces are being transferred from one conveyor to the other.

2. Coating apparatus of the kind described, comprising a first conveyor for carrying pieces to be coated, a first spray head mounted above said conveyor, a second conveyor having the receiving end thereof. beneath the delivery. end of said first mentioned conveyor, a second spray head mounted above the said second conveyor, said conveyors being arranged to travel in opposite directions and in respective paths which are laterally off-set from each other horizontally and transfer mechanism for transferring pieces from said first mentioned conveyor to said second mentioned conveyor and turning the pieces over in the transfer including means for engaging the pieces at the delivery end of said first mentioned conveyor'and retaining the pieces in contact with the conveyor to a point above the receiving end of said second mentioned conveyor.

3. A coating apparatus of the kind described, comprising a conveyor for carrying pieces to be coated, means adjacent said conveyor for spraying a coating material on to said pieces except on one side in contact with the conveyor, a second conveyor arranged with the receiving end thereof adjacent the discharge end of the first-mentioned conveyor, means for transferring the said, pieces from the discharge end of the first-mentioned conveyor'to the .receiving end of the secondmentioned conveyor and for turning the pieces over during their transfer, and means adjacent to said second conveyor for spraying the coating material on to the said one side of said pieces.

4. Coating apparatus of the kind described, comprising a continuous belt conveyor for carrying pieces to be coated, means for spraying a coating material on to the exposed surface of said pieces except on one side in contact with said conveyor, a second conveyor for carrying said pieces and mounted with the receiving end thereof below the discharge end of the first-mentioned conveyor, means for transferring the pieces from the discharge end of the first-mentioned conveyor to the receiving end of the second-mentioned conveyor and for turning the pieces over during the transfer, and means adjacent to'said second conveyor for spraying the coating material on to the said one side of said pieces.

5. Apparatus for providing articles with a spray coating, comprising a spray chamber containing the coating material in the form of a sprayed mist, a conveyor for carrying the articles to be spray-coated, means for moving the conveyor to carry the articles through said chamber, a spray head for discharging the spray material into said chamber to set up a spray mist therein, means for cutting-off the discharge from said spray head, and means to operate said cut-off means regularly and recurrently in automatic timed relation to the movement of said conveyor while maintaining a continuous supply of spray mist in said chamber.

6. Apparatus according to claim 5 in whichsaid cut-off means includes a valve in the spray head, and said last-mentioned means includes means to apply air pressure to control the closing of said valve, another valve for controlling the application of said air pressure, and electromagnetic means for recurrently operating said control valve in timed relation to the movement of said conveyor.

7. Apparatus according to claim 5 in which said cut-off means includes a valve in the spray head, and the said last-mentioned means includes a control Walve for applying air pressure to close the first-mentioned valve, an .electromagnetic device for operating said control valve, a switch for controlling the circuit of said device, a rotatable cam for operating said switch, and means to rotate said cam in timed relation with the movement of said conveyor.

GERHARD GUNTHER SCHNEIDER. CLIFFORD J. HUGHES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

